[W126 Coupe] Long term Battery drain problem

[Vance Rowley]

Hi Dan,

 Couldn't agree more, problem is going to be where to disconnect some of the circuits after this relay. The hazards for example. I know this relay controls them, but I wouldn't know where to look to break the connection between the relay and the hazards (unless I just remove all the lamps). However, some good news is since my last post, I have been going through the manual and found that this relay does in fact also control the heated rear window with a 30 minute timer to switch off, after it has been turned on (and presumably turn back on again after so much time).

One theory I have come up with, is if the relay itself has some internal problem or partial intermittent short circuit, even though the heated rear window should not be able to be switched on with the ignition off, the fuse (#3) is actually hot at all times and feeds the rear heated window when switched on. The relay itself is fed via fuse#2 which is also hot at all times. So perhaps the next step is to re-fit the relay, but disconnect fuse #3. this should prevent (if the theory is correct) any large current flow through the heated rear window matrix if this 30 minute timer for example decides to switch itself on and off intermittently. I can't really think of much else. I have never seen for example the hazards come on by themselves, or seen the washer/wipers decide to suddenly turn themselves on. But I am staying open minded on this one. So if you have any more ideas, please don't hesitate to pass on the info. It's ideas from many members on this list that I have managed to get so far. 

Thanks,
Vance

P.S. I have seen this relay on Ebay being sold by seller known as "rare79" this wouldn't happen to be one of the members of this group would it? 

----- Original Message ----- 
From: "Dan Landiss" <dan at landiss.com>
To: "Vance Rowley" <vance.rowley at tiscali.co.uk>; "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>
Sent: Monday, March 13, 2006 10:55 PM
Subject: Re: [W126 Coupe] Long term Battery drain problem


> Vance Rowley wrote:
>> I am not sure where to go next if that fails, as all of the circuits that are currently not energised without this relay, all seem to work perfectly with it (except for the fact it drains my battery with this intermittent current draw)
>>
>> Anyone any ideas where to look next? or should I just buy a new relay and hope that it's the relay itself?
>>   
> 
> I wouldn't buy a new relay until I tried disconnecting each of the 
> circuits known to be associated with it. "Working normally" is great, 
> but if one of those circuits has an intermittent short it would still 
> seem "normal" except when that short decided to materialize.
> 
> -- 
> 
> =-=-=-=-=-=-=-=-
> "Progress is brought about by doubt, not accord."  --John Amos Comenius, 17th century educator
> =-=-=-=-=-=-=-=-
> 
>
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